System and method for maintenance of transitive closure of a graph and user authentication

ABSTRACT

A user authorization system may include a database server maintaining, in a database, a cached user rights list specifying associations between users and related entities from which the users inherit rights and an access control list specifying permissions of entities to access objects. A server may receive a request from a user to access an object and pass access information to the database server. The database server may filter the access control list based on the cached user rights list to generate a filtered access control list specifying permissions to the object for the user and return the filtered access control list to the server. The server may then utilize the filtered access control list returned from the database server to determine whether the user has permission to access the object.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a conversion of, and claims a benefit of priorityunder 35 U.S.C. §119 from U.S. Provisional Application No. 61/970,214,filed Mar. 25, 2014, entitled “SYSTEM AND METHOD FOR MAINTENANCE OFTRANSITIVE CLOSURE OF A GRAPH AND USER AUTHENTICATION,” which is herebyfully incorporated by reference herein.

TECHNICAL FIELD

This disclosure relates generally to role-based access control toenterprise data. More particularly, embodiments disclosed herein relateto a system, method, and computer program product for managing andmaintaining transitive closure for role-based access control and userauthentication.

BACKGROUND OF THE RELATED ART

Current systems that rely on hierarchical role-based access control mayuse an application server that controls access to documents and adatabase that maintains explicit group memberships. In order to controlaccess, the application server must know the effective group membershipsfor a principal when checking their authorization to a resource. In ahierarchical role-based access control system, the hierarchy may benested to any depth. For example, given the group structure where User 1is a member of Groups A and B, Group B is a member of Groups D and E,and Group E is a member of Group F, then User 1 may be effectively inGroups D, E and F. In this case, membership of User 1 in Group B implieseffective membership in Group D and Group E and effective membership inGroup E implies effective membership in Group F.

In some systems, each thread of an application server may cache a userrights list that provides effective group memberships. In this case,there is a separate user rights list cache per thread on the applicationserver. There may be many application servers, each running manythreads, which leads to very low cache hit rates. The low cache hit rateforces excessive re-computation of user rights lists, which is very CPU(central processing unit) intensive. Moreover, transfer of membershiplists or user rights lists (which may contain hundreds of thousands ofentries) between the database server, and the application server is veryslow.

SUMMARY OF THE DISCLOSURE

It is an object of the invention to improve rights list and/or accesscontrol list (ACL) filters management. Particularly, it is an object ofthe invention to improve access control scalability and performance forcontent servers or content management systems.

In some embodiments, these and other objects of the invention may berealized in a special database server having a transitive closuremanagement module. The transitive closure management module may beembodied on non-transitory computer readable medium and includeinstructions translatable to perform particular functions, includingreceiving an identification of an entity defined in a database storing acached transitive closure and interacting with a relational databasemanagement system according to a relational query language toincrementally update the cached transitive closure stored in thedatabase. In some embodiments, the transitive closure management modulemay incrementally update the cached transitive closure by generating anew transitive closure for the entity and determining a deletetransitive closure record. In some embodiments, the delete transitiveclosure record may be determined by the transitive closure managementmodule analyzing the cached transitive closure and the new transitiveclosure, determining a first transitive closure path for the entity thatis not specified in the new transitive closure and that is specified inthe cached transitive closure, and selecting as the delete transitiveclosure record a record specifying the first transitive closure path.The transitive closure management module may then delete the deletetransitive closure record from the cached transitive disclosure.

In some embodiments, a user authorization system may include a databaseserver maintaining, in a database, a cached user rights list specifyingassociations between users and related entities from which the usersinherit rights and an access control list specifying permissions ofentities to access objects. A server, such as an authorization server,an application server, a content server, etc., may receive a requestfrom a user to access an object and pass access information to thedatabase server. The object may be managed by the server and may haveits own access control list. The database server may filter the accesscontrol list based on the cached user rights list to generate a filteredaccess control list specifying permissions to the object for the userand return the filtered access control list to the server. The servermay then utilize the filtered access control list returned from thedatabase server to determine whether the user has permission to accessthe object. The filtered access control list may contain only accesscontrol list entries that apply to the user and the object.

One embodiment may comprise a system having a processor and a memory andconfigured to implement a method disclosed herein. One embodiment maycomprise a computer program product that comprises a non-transitorycomputer-readable storage medium which stores computer instructions thatare executable by at least one processor to perform the method. Numerousother embodiments are also possible.

These, and other, aspects of the disclosure will be better appreciatedand understood when considered in conjunction with the followingdescription and the accompanying drawings. It should be understood,however, that the following description, while indicating variousembodiments of the disclosure and numerous specific details thereof, isgiven by way of illustration and not of limitation. Many substitutions,modifications, additions and/or rearrangements may be made within thescope of the disclosure without departing from the spirit thereof, andthe disclosure includes all such substitutions, modifications, additionsand/or rearrangements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating one embodiment of a transitiveclosure system.

FIG. 2 is a diagram illustrating one embodiment of a graph and atransitive closure.

FIG. 3 is a diagram illustrating one embodiment of an updated graph andtransitive closure.

FIGS. 4A-4E are diagrams illustrating one embodiment of updating acached transitive closure.

FIG. 5 is a flow chart illustrating one embodiment of incrementallydeleting entries from a cached transitive closure.

FIG. 6 is a flow chart illustrating one embodiment of incrementallyinserting entries in a cached transitive closure.

FIG. 7 is a diagram illustrating one embodiment of a system updating acached transitive closure.

FIGS. 8A-8G are diagrams illustrating another embodiment of updating acached transitive closure.

FIG. 9 is a diagram illustrating one embodiment of an authorizationsystem.

FIG. 10 is a diagram illustrating one embodiment of an authenticationsystem.

DETAILED DESCRIPTION

Systems and methods of maintaining transitive closure and the variousfeatures and advantageous details thereof are explained more fully withreference to the nonlimiting embodiments that are illustrated in theaccompanying drawings and detailed in the following description.Descriptions of well-known starting materials, processing techniques,components and equipment are omitted so as not to unnecessarily obscurethe invention in detail. It should be understood, however, that thedetailed description and the specific examples, while indicatingpreferred embodiments of the invention, are given by way of illustrationonly and not by way of limitation. Various substitutions, modifications,additions and/or rearrangements within the spirit and/or scope of thisdisclosure will become apparent to those skilled in the art from thisdisclosure.

FIG. 1 is a diagrammatic representation of a transitive closure system100 comprising a database server 105 coupled to one or more additionalservers 110 or other computing devices, by a network 115. Databaseserver 105 may include a database management system (DMS) 120, such as arelational database management system (RDMS) other database managementsystem that manages a database 125. According to one embodiment, DMS 120may support a relational query language, such as SQL, or otherrelational query language. Database server 105, an authorization serveror other server 110 may also include a transitive closure module 130that can interact with DMS 120 using the relational query language orother interface.

Database 125 may contain various tables 135 including records forvarious entities. The entities may vary based on application. Forexample, for an access control system, the entities may include users,groups (including roles), files, directories and other entities whereasfor a travel application, the entities may include cities, flights,customers, fares, promotions or other entities. In any event, database125 may include a graph 140 expressing edges between entities indatabase 125. Graph 140 may be explicitly entered, generated by DMS 120or otherwise provided. According to one embodiment graph 140 can be adirected acyclic graph.

Database 125 may also store a cached transitive closure 145 for some orall of the entities in graph 140. A cached transitive closure record foran entity specifies that there is a path in graph 140 from that entityto the associated entity. Using the example of cached transitive closurerecord 150 for Entity 1, there is a transitive closure record 150 thatspecifies the transitive closure path {Entity 1, Entity 5}, reflectingthe edge {Entity 1, Entity 4} and edge {Entity 4, Entity 5} in graph140. According to one embodiment, transitive closure module 130 maygenerate queries to DMS 120 to cause creation of cached transitiveclosure 145, which may be a transitive closure of graph 140.

In some cases, cached transitive closure 145 may be used when respondingto requests from server 110 or other computing device. In servicing arequest, transitive closure module 130 may determine a database entityrelevant to the request and interact with DMS 120 to retrieveinformation from database 125 based on the cached transitive closurerecords for the entity. However, if graph 140 has changed, cachedtransitive closure 145 may be out of date. To address this issue,transitive closure module 130 may maintain state information 155 totrack when the status of graph 140 changes.

When transitive closure module 130 receives a request relevant to anentity, transitive closure module 130 can check state information 155 todetermine if the cached transitive closure records for the entity areout of date. If not, the request can be serviced using the cachedtransitive closure records. If the records are out of date, transitiveclosure module 130 can interact with DMS 120 to update cached transitiveclosure 145.

The transitive closure of graph 140 for an entity may include thousands,tens of thousands, millions or more entries. Consequently, updating theentire transitive closure for the entity may require a substantialamount of time. To obviate this problem, embodiments of transitiveclosure module 130 may interact with DMS 120 to incrementally updatecached transitive closure 145.

Before discussing incremental updates to cached transitive closure 145,some additional context may be helpful. FIG. 2 is a diagrammaticrepresentation of one embodiment of an initial state of graph 140 andthe corresponding directed edge-node representation 200 illustrating thedirect relationships between entities expressed in graph 140. FIG. 2also illustrates an initial state of transitive closure 145 of graph 140and the corresponding edge-node representation 210 further showing thetransitive closure paths from Entity 1 and Entity 2, as denoted by thedashed lines. It may be noted that in some cases, only the transitiveclosures of certain entities are maintained. For example, while cachedtransitive closure 145 includes records for all the transitive closurepaths that can be derived from graph 140, cached transitive closure 145,in other embodiments, may only include transitive closure records for acertain subset of entities in graph 140 (e.g., Entity 1 and Entity 2).

FIG. 3 is a diagrammatic representation of graph 140 being updated fromthe initial state to a new state (represented by graph 140′) and thecorresponding updated edge-node graph representation 300 with newconnections in bold. FIG. 3 also illustrates cached transitive closure145 updated to cached transitive closure 305 of graph 140′ and includingthe transitive closure paths that can be derived from graph 140′.Edge-node representation 315 illustrates the transitive closure pathsfor Entity 1 and Entity 2 according to cached transitive closure 305(new paths denoted by bold dashed lines). However, updating transitiveclosure 145 for all entities (even if transitive closure 145 onlyincludes transitive closures for a subset of entities in graph 140) canbe time consuming and may not be necessary to service particularrequests. Accordingly, transitive closure 145 may be incrementallyupdated.

According to one embodiment, to incrementally delete records, a newtransitive closure R′ for an entity is calculated. The set theoreticdifference of cached transitive closure (R) and a newly computedtransitive closure (R′) can be determined according to (R\R′) todetermine a set of delete records (D), and the resulting rows deletedfrom the cache in the database. Thus, R_(i+1)=R_(i)−D for removingrecords.

To incrementally insert records, the set theoretic difference of a newlycomputed transitive closure (R′) and a cached transitive closure (R) canbe determined according to (RAR) to determine a set of insert records(I) and resulting records added to the cache. Thus, R_(i+1)=I+R_(i) forinserting records.

FIGS. 4A-4E illustrate one embodiment of incrementally updating cachedtransitive closure 145. While incremental deletion is described beforeincremental insertion, incremental insertion may occur first. The stepsof FIGS. 4A-4E can be implemented through issuing appropriate queries toa database (e.g., by transitive closure module 130 sending queries toDMS 120 of FIG. 1).

FIG. 4A is a diagrammatic representation of generating a new transitiveclosure. When a request is received (e.g., by transitive closure module130 of FIG. 1) for which transitive closure records for an entity willbe used and the cached transitive closure records for the entity are outof date, a new transitive closure 400 of the current graph can begenerated for the entity. FIG. 4A, for example, illustrates that a newtransitive closure 400 of updated graph 140′ can be generated for Entity1. New transitive closure 400 can be produced by an in-memory structuresuch as a common table expression (CTE) that is temporarily held inmemory. While in FIG. 4A, new transitive closure 400 only includestransitive closure records for a specific entity; new transitive closure400 may include records for multiple entities in other embodiments.

FIG. 4B is a diagrammatic representation illustrating that the cachedtransitive closure records for the entity (e.g., cached transitiveclosure records 405 for Entity 1) and the new transitive closure 400 canbe analyzed to determine a difference of cached transitive closurerecords 405 and new transitive closure 400 to identify a set of deleterecords 410. In this case, delete records 410 include the transitiveclosure paths for Entity 1 found in cached transitive closure 145 andnot in new transitive closure 400.

FIG. 4C is a diagrammatic representation illustrating that a set ofdelete records 410 may be deleted from cached transitive closure 145 toupdate cached transitive closure 145 (represented by updated cachedtransitive closure 145′).

FIG. 4D is a diagrammatic representation illustrating that a set ofinsert records 420 can be determined based on a difference of newtransitive closure 400 and cached transitive closure records 405′.Insert records 420 can be records that contain transitive closure pathsfound in new transitive closure 400 but not the cached transitiveclosure 145′. In the example of FIG. 4D, record 401 illustrates adifference of new transitive closure 400 and cached transitive closurerecords 405′. FIG. 4E is a diagrammatic representation illustrating thatthe set of insert records 420 (which, in this example, comprises record401, as determined by the steps illustrated in FIG. 4D) can be added tocached transitive closure 145′ to create updated cached transitiveclosure 145″.

FIG. 5 is a flow chart illustrating one embodiment of incrementallyupdating a cached transitive closure to delete records. The method ofFIG. 5 can be implemented, for example, by transitive closure module130. At step 502, the entity for which a transitive closure update isrequired can be determined. At step 506, a new transitive closure forthe entity is generated. The new transitive closure for the entity canbe determined from a persistent or temporary graph of database entities.At step 508, a record for the entity from the cached transitive closurecan be selected. The cached transitive closure record and new transitiveclosure for the entity can be analyzed to determine if the cachedtransitive closure record specifies a transitive closure path that isalso specified in the new transitive closure (step 510). If the recordspecifies a transitive closure path not specified in the new transitiveclosure, the cached transitive closure record can be selected as adelete record (step 512). Each cached transitive closure record for theentity can be evaluated to determine the set of delete records (step514). At step 516, the delete records can be deleted from the cachedtransitive closure. The steps of FIG. 5 can be repeated as needed ordesired.

FIG. 6 is a flow chart illustrating one embodiment of incrementallyupdating a cached transitive closure to insert records. The method ofFIG. 6 can be implemented, for example, by transitive closure module130. At step 602, the entity for which a transitive closure update isrequired can be determined. At step 604, a new transitive closure forthe entity is generated. The new transitive closure for the entity canbe determined from a persistent or temporary graph of database entities.At step 608, a record for the entity from the new transitive closure canbe selected. The cached transitive closure and new transitive closurerecord for the entity can be analyzed to determine if the new transitiveclosure record specifies a transitive closure path that is alsospecified in the cached transitive closure (step 610). If the newtransitive closure record specifies a transitive closure path notspecified in the cached transitive closure, a new record can be insertedinto the cached transitive closure for the transitive closure path (step614). Each new transitive closure record for the entity can be evaluatedto determine the complete set of records to insert (step 612). The stepsof FIG. 6 can be repeated as needed or desired.

FIG. 7 illustrates one embodiment of an authentication system in which adatabase server 705 maintains a database 725 including a cached userrights list 735. Cached user rights list 735 provides transitive closurepaths between users and related entities from which the users inheritrights. The related entities may comprise groups, roles or otherentities.

Database server 705 or other computing device (e.g., application server710) may maintain a set of state information used to determine whethercached transitive closure list 735 is stale. According to oneembodiment, server 705 maintains a state number for each user, and aglobal system state. When that user is added to or removed from anygroup, that user's state number is incremented. When a group is added toor removed from any other group the global system state changes. Ifeither the user state or global system state has changed since thetransitive closure for the user was last determined, cached transitiveclosure list 735 can be considered stale.

An application server 710 can communicate with database server 705. Whena user 750 makes a request for an object (e.g., a document, file,directory or other object), application server 710 can pass a useridentifier (ID) 755 associated with the user to database server 705(e.g., in a query). If the cached transitive closure list 735 isconsidered stale for the user, database server 705 can determine a newtransitive closure from the user from a membership graph (see e.g., FIG.8A), determine a difference of cached transitive closure list 735 andthe new transitive closure 740 to determine the resulting delete records745 and delete the appropriate rows from transitive closure list 735 toupdate cached user rights list 735 (as represented by user rights list735′). Database server 705 can further determine a difference of userright list 735′ and new transitive closure 740 to determine a set ofinsert records 747 and insert the insert records 747 into the cacheduser right list 735′ to update the cached user rights list (asrepresented by cached user rights list 735″). Insertion may occur beforeor after deletion.

FIG. 8A-8G are diagrammatic representations of another embodimentincrementally updating a user rights list. FIG. 8A illustrates aninitial state of a membership graph 800 containing explicit user andgroup memberships with corresponding edge-node representation 810 and aninitial state of transitive closure 805 of membership graph 800 andcorresponding edge-node graph 815 showing the initial transitive closurepaths (in this case effective rights) for each user. Cached transitiveclosure 805 can provide a rights list that associates each user withother database entities from which the user inherits rights.

FIG. 8B illustrates updated graph 800′ and edge-node representation 810′and updated edge-node graph 815′ showing the effective rights for User 1and User 2 that should be in effect according to graph 800′. However, ifcached transitive closure 805 has not yet been updated, cachedtransitive closure 805 will not include the appropriate effectiverights.

FIG. 8C illustrates that a new transitive closure 820 can be created forUser 1. New transitive closure 820 can include i) a set of newtransitive closure records 822 reflecting relationships explicitlydefined in the membership graph and ii) new transitive closure records824 that are derived by selecting an endpoint for a transitive closurepath already in new transitive closure 820 and creating transitiveclosure records for User 1 using the directed relationships from theendpoint in graph 800′. Thus, for example, because the path {User 1,Group C} is in new transitive closure 820, Group C can be used to findadditional paths from graph 800′. In this case, graph 800′ can beanalyzed to determine that there is a direct relationship from Group Cto Group F. Consequently, record 826 can be added to new transitiveclosure 820 for the path {User 1, Group F}. This process can be repeatedusing Group F from new transitive closure 820 to identify additionalpaths from graph 800′ (of which there are none in this example) and soon.

FIG. 8D illustrates that a difference of cached transitive closure 805and new transitive closure 820 for an entity (e.g., User 1) can bedetermined to provide a set of delete records 825. FIG. 8E illustratesthat the difference 825 can be subtracted from the cached transitiveclosure 805 to create updated cached transitive closure 805′. It can benoted that the records deleted comprise a transitive closure path {User1, Group E} that was found in the cached transitive closure 805, but notthe new transitive closure 820.

FIG. 8F illustrates that the insert records 840 can be determined fromthe difference of new transitive closure 820 and cached transitiveclosure 805′. FIG. 8G illustrates that insert records 840 can beinserted into cached transitive closure 805′ to create updatedtransitive closure 805″.

One embodiment of a method for incrementally deleting records andinserting records can be implemented according the followingpseudo-code. The queries can be passed to a database management systemfrom code running on the same computing device or another computingdevice. In some cases, the code may be stored and executed from thedatabase. It can be noted that specific query commands may be specificto certain database management systems. However, one of ordinary skillin the art would understand that other queries can also be used.

DECLARE @ChildID BIGINT = <userID>; WITH TransitiveClosure (RLID,ChildID, RLRightID) AS (  SELECT   @ChildID AS RLID, ChildID, ID ASRLRightID  FROM   Memberships  WHERE ChildID in (@ChildID)  UNION ALL SELECT   @ChildID AS RLID, E.ChildID, E.ID  FROM    Memberships AS E   join TransitiveClosure AS M ON E.ChildID = M.RLRightID ) DELETE FROMTransitiveClosureCache FROM  (   SELECT * FROM TransitiveClosureCacheWHERE RLID = @ChildID   EXCEPT    SELECT * FROM     (      SELECT RLID,RLRightID FROM TransitiveClosure      UNION ALL      SELECT @ChildID,@ChildID    )  ) AS to_delete WHERE  to_delete.RLID =TransitiveClosureCache.RLID  and to_delete.RLRightID =TransitiveClosureCache.RLRightID; DECLARE @ChildID BIGINT = <userID>;WITH TransitiveClosure (RLID, ChildID, RLRightID) AS (  SELECT   @ChildID AS RLID, ChildID, ID AS RLRightID  FROM    Memberships WHERE ChildID in (@ChildID)  UNION ALL  SELECT    @ChildID AS RLID,E.ChildID, E.ID  FROM   Memberships AS E   join TransitiveClosure AS MON E.ChildID = M.RLRightID ) INSERT INTO TransitiveClosureCache SELECTRLID, RLRightID FROM TransitiveClosure EXCEPT SELECT * FROMTransitiveClosureCache WHERE RLID = @ChildID;

In this example, updating the transitive closure has approximately thesame complexity under addition of a membership as it has under deletionof a membership.

FIG. 9 is a diagrammatic representation of one embodiment of a systemfor controlling access to resources, such as files, directories, topics,replies, task lists, task groups, blogs, blog entries or other resource.According to one embodiment, a database server 905 may maintain adatabase 925 of user rights and access control permissions. A user 950can connect to an application server 910 and request a set of resources(documents, folders, etc. . . . ). A set of access information 955 canbe passed to database server 905. Access information 955, according toone embodiment, can include the user's ID and the identity of objectsthe user is requesting. In some embodiments, access information 955 maybe sent as part of queries to filter an access control list.

Access control list entries for the requested objects can be filteredagainst a user's rights list 935 cached in the database 925 (see e.g.,FIG. 10). User rights list 935 can be a cached transitive closure of amembership graph as discussed above. In some cases, the user rights list935 may be updated prior to filtering. A filtered set of ACL entries 960are returned to the application server 910. Application server 910checks the user's permissions using filtered ACL entries 960 and theobjects to which the user has permission are returned.

FIG. 10 is a block diagram illustrating one embodiment of anauthentication system. A database server (such as database server 105 ordatabase server 905) may include a database management system (DMS)1005, such as a relational database management system (RDMS) otherdatabase management system that manages a database 1010. According toone embodiment, DMS 1010 may support a relational query language, suchas SQL, or other relational query language. The database server, anauthorization server or other server or computing device may include anauthorization module 1000 that can interact with DMS 1005 using therelational query language or other interface.

Database 1010 may contain various tables including records for variousentities. The entities may vary based on application. For example, foran access control system, the entities may include users, groups, roles,files, directories and other entities whereas for a travel application,the entities may include cities, flights, customers, fares, promotionsor other entities. In any event, database 1010 may include a user rightslist 1015 as a cached transitive closure. Database 1010 may also includean Access Control List 1020 for a set of objects.

Access Control List (ACL) 1020 can contain several Access ControlEntries (ACEs). In some cases each object may have its own ACL. In otherembodiments, the ACL may include entries for multiple objects.Permissions may be mapped between objects and users/groups in anysuitable manner. For example, in one embodiment, an ACE maps an objectto user or group, and the permissions the user or group has on thatobject.

In other embodiments, policies can be abstracted from objects so thatpermissions are set based on policies and objects are associated withpolicies:

When a user requests an object or set of objects, the user's ID andobject identities can be passed to authorization module 1000.Authorization module 1000 can query DMS to determine a filtered ACL1025. The filtered ACL 1025 contains the ACL entries that match both anobject requested by the user and a user/group associated with the userin the user rights list 1015. According to one embodiment, only the ACLentries that apply to the requesting user and requested objects arereturned and used in checking permissions for a request.

As discussed above, embodiments may use a relational database forcomputation of the transitive closure. As some relational databases donot support cycles it may not be possible to determine a transitiveclosure from an arbitrary directed graph. As would be understood bythose of ordinary skill in the art, however, a graph containing cyclescan be represented equally well as a directed acyclic graph.Accordingly, a graph containing cycles can be transformed into adirected acyclic graph with no loss (e.g., a graph with cycles can betransformed into a directed acyclic graph in the context of anauthorization system, with no loss in authorizations). Furthermore,while discussed primarily in terms of an authorization system,embodiments can apply to other systems where a directed graph is used.

Embodiments described herein provide several advantages. In someembodiments, a database server may provide a single cached transitiveclosure (or a relatively small number of cached transitive closures)that can be used to service requests from multiple application serversor multiple threads in an application server. Accordingly, there can bea single cache (or small number of caches) in the database, rather thanhundreds of individual caches in server threads, dramatically increasingthe cache hit ratio and reducing CPU usage spent re-computing thetransitive closure of the graph.

Additionally, because some embodiments can update the transitive closureincrementally, disk I/O operations are decreased. Embodiments provideanother advantage, because the transitive closure does not have to betransferred between the database and the application server to provideauthorization, reducing network resources.

By eliminating a need to transfer membership lists or user rights lists(which may contain hundreds of thousands of entries) between databaseservers and application servers, embodiments disclosed herein canprovide significant performance improvements to systems that utilizemembership lists or user rights lists to perform required and/or desiredfunctions such as task management, workflow status updates. Furthermore,embodiments disclosed herein can improve the CPU utilization byapplication servers as they are no longer required to compute andre-compute user rights lists. To this end, embodiments disclosed hereincan also improve systems where a rights list is retrieved for varioususes, for instance, to reflect a group membership change, distributenotifications, grant user permissions, personalize menu items (e.g.,user-specific assignments, group membership(s), projects, task lists,workflows, etc.), determine security clearance, determine workflowpermissions, etc.

Routines, methods, steps, operations or portions thereof describedherein can be implemented through control logic, including computerexecutable instructions stored on a computer readable medium, hardware,firmware or a combination thereof. The control logic can be adapted todirect an information processing device to perform a set of stepsdisclosed in the various embodiments. Some embodiments may beimplemented by using software programming or code in one or more digitalcomputers, by using application specific integrated circuits,programmable logic devices, field programmable gate arrays, optical,chemical, biological, quantum or nanoengineered systems, components andmechanisms. Based on the disclosure and teachings provided herein, aperson of ordinary skill in the art will appreciate other ways and/ormethods to implement the invention.

Computer executable instructions or code can be stored in acomputer-readable medium and can be operated on by a processor to permita computer to perform functions, steps, operations, methods, routines,operations or portions thereof described herein. Any suitable languagecan be used including C, C++, Java, JavaScript, assembly language orother programming or scripting code. Different programming techniquescan be employed such as procedural or object oriented. In an embodiment,HTML may utilize JavaScript to provide a means of automation andcalculation through coding.

Any particular step, operation, method, routine, operation or portionthereof can execute on a single computer processing device or multiplecomputer processing devices, a single computer processor or multiplecomputer processors. Data may be stored in a single storage medium ordistributed through multiple storage mediums, and may reside in a singledatabase or multiple databases (or other data storage). The sequence ofoperations described herein can be interrupted, suspended, or otherwisecontrolled by another process, such as an operating system, kernel, etc.The routines can operate in an operating system environment or asstand-alone routines.

A “computer-readable medium” may be any type of data storage medium thatcan store computer instructions, including, but not limited to read-onlymemory (ROM), random access memory (RAM), hard disks (HD), datacartridges, data backup magnetic tapes, floppy diskettes, flash memory,optical data storage, CD-ROMs, or the like. The computer readable mediumcan be, by way of example, only but not by limitation, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, system, device, or computer memory. The computer readablemedium may include multiple computer readable media storing computerexecutable instructions, such as in a distributed system or instructionsstored across an array.

A “processor” includes any hardware system, hardware mechanism orhardware component that processes data, signals or other information. Aprocessor can include a system with a central processing unit, multipleprocessing units, dedicated circuitry for achieving functionality, orother systems. Processing need not be limited to a geographic location,or have temporal limitations. For example, a processor can perform itsfunctions in “real-time,” “offline,” in a “batch mode,” etc. Portions ofprocessing can be performed at different times and at differentlocations, by different (or the same) processing systems.

It will be understood for purposes of this disclosure that a service ormodule is one or more computer devices, configured (e.g., by a computerprocess or hardware) to perform one or more functions. A service maypresent one or more interfaces which can be utilized to access thesefunctions. Such interfaces include APIs, interfaces presented for a webservices, web pages, remote procedure calls, remote method invocation,etc.

Embodiments can be implemented in a computer communicatively coupled toa network (for example, the Internet, an intranet, an internet, a WAN, aLAN, a SAN, etc.), another computer, or in a standalone computer. As isknown to those skilled in the art, the computer can include a centralprocessing unit (“CPU”) or processor, memory (e.g., primary or secondarymemory such as RAM, ROM, HD or other computer readable medium for thepersistent or temporary storage of instructions and data) and one ormore input/output (“I/O”) device(s). The I/O devices can include akeyboard, monitor, printer, electronic pointing device (for example,mouse, trackball, stylus, etc.), touch screen or the like. Inembodiments, the computer has access to at least one database on thesame hardware or over the network.

Steps, operations, methods, routines or portions thereof of the presentinvention may be implemented on one computer or shared among two or morecomputers. In one embodiment, the functions of the present invention maybe distributed in the network. Communications between computersimplementing embodiments of the invention can be accomplished using anyelectronic, optical, radio frequency signals, or other suitable methodsand tools of communication in compliance with network and othercommunications protocols.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, article, orapparatus.

Further, unless expressly stated to the contrary, “or” refers to aninclusive or and not to an exclusive or. That is, the term “or” as usedherein is generally intended to mean “and/or” unless otherwiseindicated. For example, a condition A or B is satisfied by any one ofthe following: A is true (or present) and B is false (or not present), Ais false (or not present) and B is true (or present), and both A and Bare true (or present).

As used herein, a term preceded by “a” or “an” (and “the” whenantecedent basis is “a” or “an”) includes both singular and plural ofsuch term unless the context clearly dictates otherwise. Also, as usedin the description herein, the meaning of “in” includes “in” and “on”unless the context clearly dictates otherwise.

Additionally, any examples or illustrations given herein are not to beregarded in any way as restrictions on, limits to, or expressdefinitions of, any term or terms with which they are utilized. Instead,these examples or illustrations are to be regarded as being describedwith respect to one particular embodiment and as illustrative only.Those of ordinary skill in the art will appreciate that any term orterms with which these examples or illustrations are utilized willencompass other embodiments which may or may not be given therewith orelsewhere in the specification and all such embodiments are intended tobe included within the scope of that term or terms. Language designatingsuch nonlimiting examples and illustrations includes, but is not limitedto: “for example,” “for instance,” “e.g.,” “in one embodiment.”

Reference throughout this specification to “one embodiment,” “anembodiment,” or “a specific embodiment” or similar terminology meansthat a particular feature, structure, or characteristic described inconnection with the embodiment is included in at least one embodimentand may not necessarily be present in all embodiments. Thus, respectiveappearances of the phrases “in one embodiment,” “in an embodiment,” or“in a specific embodiment” or similar terminology in various placesthroughout this specification are not necessarily referring to the sameembodiment. Furthermore, the particular features, structures, orcharacteristics of any particular embodiment may be combined in anysuitable manner with one or more other embodiments. It is to beunderstood that other variations and modifications of the embodimentsdescribed and illustrated herein are possible in light of the teachingsherein and are to be considered as part of the spirit and scope of theinvention.

Although the invention has been described with respect to specificembodiments thereof, these embodiments are merely illustrative, and notrestrictive of the invention. The description herein of illustratedembodiments of the invention is not intended to be exhaustive or tolimit the invention to the precise forms disclosed herein (and inparticular, the inclusion of any particular embodiment, feature orfunction is not intended to limit the scope of the invention to suchembodiment, feature or function). Rather, the description is intended todescribe illustrative embodiments, features and functions in order toprovide a person of ordinary skill in the art context to understand theinvention without limiting the invention to any particularly describedembodiment, feature or function. While specific embodiments of, andexamples for, the invention are described herein for illustrativepurposes only, various equivalent modifications are possible within thespirit and scope of the invention, as those skilled in the relevant artwill recognize and appreciate. As indicated, these modifications may bemade to the invention in light of the foregoing description ofillustrated embodiments of the invention and are to be included withinthe spirit and scope of the invention. Thus, while the invention hasbeen described herein with reference to particular embodiments thereof,a latitude of modification, various changes and substitutions areintended in the foregoing disclosures, and it will be appreciated thatin some instances some features of embodiments of the invention will beemployed without a corresponding use of other features without departingfrom the scope and spirit of the invention as set forth. Therefore, manymodifications may be made to adapt a particular situation or material tothe essential scope and spirit of the invention.

In the description herein, numerous specific details are provided, suchas examples of components and/or methods, to provide a thoroughunderstanding of embodiments of the invention. One skilled in therelevant art will recognize, however, that an embodiment may be able tobe practiced without one or more of the specific details, or with otherapparatus, systems, assemblies, methods, components, materials, parts,and/or the like. In other instances, well-known structures, components,systems, materials, or operations are not specifically shown ordescribed in detail to avoid obscuring aspects of embodiments of theinvention. While the invention may be illustrated by using a particularembodiment, this is not and does not limit the invention to anyparticular embodiment and a person of ordinary skill in the art willrecognize that additional embodiments are readily understandable and area part of this invention.

Although the steps, operations, or computations may be presented in aspecific order, this order may be changed in different embodiments. Insome embodiments, to the extent multiple steps are shown as sequentialin this specification, some combination of such steps in alternativeembodiments may be performed at the same time. The sequence ofoperations described herein can be interrupted, suspended, or otherwisecontrolled by another process.

It will also be appreciated that one or more of the elements depicted inthe drawings/figures can also be implemented in a more separated orintegrated manner, or even removed or rendered as inoperable in certaincases, as is useful in accordance with a particular application.Additionally, any signal arrows in the drawings/figures should beconsidered only as exemplary, and not limiting, unless otherwisespecifically noted.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any component(s) thatmay cause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeature or component.

In the foregoing specification, the invention has been described withreference to specific embodiments. However, one of ordinary skill in theart appreciates that various modifications and changes can be madewithout departing from the scope of the invention. Accordingly, thespecification, including the Summary and Abstract, and figures are to beregarded in an illustrative rather than a restrictive sense, and allsuch modifications are intended to be included within the scope ofinvention. The scope of this disclosure should be determined by thefollowing claims and their legal equivalents.

What is claimed is:
 1. A user authorization system comprising: adatabase server including a database management system that manages adatabase, the database server maintaining, in the database, a cacheduser rights list as a cached transitive closure and an access controllist for a set of objects, the database embodied on non-transitorycomputer memory, the user rights list comprising user rights records ofassociations between users and related entities from which the usersinherit rights and the access control list specifying permissions ofentities to access the set of objects; and an authorization servercoupled to the database server via a network, the authorization servercomprising a processor and a memory and configured to: receive a requestfrom a user for an object; and interact with the database server tocause the database server to perform: determining a new transitiveclosure for the user based on a directed graph of associations betweenentities in the database; determining a delete user rights record by:comparing the cached user rights list and the new transitive closure;determining a first transitive closure path for an entity that is notspecified in the new transitive closure and that is specified in thecached user rights list; and selecting as the delete user rights recorda record specifying the first transitive closure path; and deleting thedelete user rights record from the cached user rights list.
 2. The userauthorization system of claim 1, wherein the authorization server isfurther configured to pass an object identifier for the object requestedby the user to the database server.
 3. The user authorization system ofclaim 2, wherein the database server is further configured to perform:filtering the access control list for the user according to the cacheduser rights list; and sending a filtered access control list to theauthorization server.
 4. The user authorization system of claim 1,wherein in determining the delete user rights record, the databaseserver is further configured to perform: determining, from the cacheduser rights list, a set of common records for the user that specifycommon associations between the user and related entities also specifiedby new transitive closure records for the user in the new transitiveclosure; and selecting as the delete user rights record, a cached userrights record for the user that is not in the set of common records forthe user.
 5. The user authorization system of claim 1, wherein indetermining the delete user rights record, the database server isfurther configured to perform: determining a set of delete user rightsrecords (D) according to D=(R\R′), where: R=a current set of cached userrights records for the user; R′=a set of new transitive closure recordsfor the user.
 6. The user authorization system of claim 1, wherein thedatabase server is further configured to perform: determining an insertrecord, said insert record specifying a second association between theuser and a second related entity, the second association specified inthe new transitive closure but not the cached user rights list; andinserting the insert record in the cached user rights list.
 7. The userauthorization system of claim 6, wherein determining the insert recordfurther comprises determining a set of insert transitive closure records(I) according to I=(R′\R), where: R=a current set of cached transitiveclosure records for the user; R′=a set of new transitive closure recordsfor the user.
 8. The user authorization system of claim 1, wherein therelated entities from which the users inherit rights comprise groups orroles.
 9. The user authorization system of claim 1, wherein the entitiesin the database comprise users, groups, roles, files, and directories.10. The user authorization system of claim 1, wherein determining thenew transitive closure for the user comprises transforming a membershipgraph containing one or more cycles to the directed graph.
 11. A userauthorization system comprising: a first server coupled to a databaseserver via a network and comprising a processor and a memory, thedatabase server including a database management system that manages adatabase embodied on a non-transitory computer readable medium andmanages and maintains user rights and access control permissions for thedatabase, the first server configured to: receive a request from a userfor an object; pass access information to the database server, theaccess information comprising a user identifier and an objectidentifier; and enforce a filtered access control list returned by thedatabase server to grant or deny access to the object by the user; thedatabase server configured to: determine a transitive closure of ahierarchy of entities that define inheritance of rights to generate auser rights list that comprises transitive closure paths between usersand related entities from which users inherit rights; maintain the userrights list in a cache in the database as a cached user rights list;maintain an access control list in the database, the access control listcomprising a first set of access control entries specifying permissionsof entities to access the object; receive the user identifier and objectidentifier passed from the first server; responsive to the accessinformation: filter the access control list based on the cached userrights list to generate the filtered access control list specifyingpermissions to the object for the user, wherein to generate the filteredaccess control list further comprises to determine a filtered set ofaccess control entries from the first set of access control entries forinclusion in the filtered access control list, the filtered set ofaccess control entries comprising access control entries from the firstset of access control entries that map the user or an entity from whichthe user inherits rights to the object; and return the filtered accesscontrol list to the first server.
 12. The user authorization system ofclaim 11, wherein the database server is further configured to:determine a first set of entities related to the user, the first set ofentities related to the user comprising entities related to the user inthe cached user rights list; and wherein the permissions to the objectfor the user in the filtered access control list comprise permissions tothe object for the first set of entities related to the user.
 13. Theuser authorization system of claim 11, wherein the related entities fromwhich the users inherit rights comprise groups or roles.
 14. The userauthorization system of claim 11, wherein the first server utilizes thefiltered access control list returned from the database server todetermine whether the user has permission to access the object.
 15. Theuser authorization system of claim 11, wherein the first servercomprises an application server or a content server.
 16. The userauthorization system of claim 11, wherein the object is managed by thefirst server and wherein each object managed by the first server has aspecific access control list.
 17. The user authorization system of claim16, wherein permissions to objects managed by the first server are setbased on policies and the objects are associated with the policies. 18.The user authorization system of claim 11, wherein the object comprisesa content resource.
 19. The user authorization system of claim 18,wherein the content resource comprises a file, a directory, a document,a folder, a topic, a reply, a task, a task list, a task group, a blog,or a blog entry.
 20. The user authorization system of claim 11, whereinthe filtered access control list contains only access control listentries that apply to the user and the object.